Synchronizing Multiple Instruments

• You can operate instruments independently with triggers and events passed between them to coordinate operations.
• You can use the NI-TClk API to phase align the internal clocks of all the instruments and route triggers deterministically so that all the instruments respond to and receive triggers at the same time.
• In the Digital Pattern Editor, you can use the same instrument group name in the pin map for multiple instruments, which automatically phase aligns the internal clocks of the instruments included in the group and routes triggers deterministically.
  Note You can group digital pattern instruments of only the same model and channel count, and the instruments must be in the same chassis. For example, you can group two PXIe-6571s of matching channel count that are within the same chassis but not a PXIe-6571 and PXIe-6570 in the same chassis.
  Note You can open a synchronized multi-instrument session by passing multiple instruments into the Initialize with Options API. Refer to the Digital Pattern User Manual for more information.

After aligning the internal clocks and routing triggers, you can use an additional module in the chassis, a PXIe-6674T, to combine pattern comparison results across digital pattern instruments and control subsequent pattern execution based on those results. Refer to the PXIe-6674T User Manual for information about installing PXIe-6674T in the timing and synchronization slot of the chassis.

Internal Clock Phase Alignment

For digital pattern instruments, the MasterClk internal clock is locked to the PXIe_CLK100 signal. To ensure that other instruments synchronize with a digital pattern instrument, their internal clocks, which are sometimes called Sample clocks, must also be locked to PXIe_CLK100.

System Timing Alignment

The NI-TClk API included with an installation of the NI-Digital Pattern Driver aligns the timing reference on synchronized instruments. For instruments used inside a Semiconductor Test System (STS), the timing calibration procedure aligns the timing across all digital instrument channels. On systems without STS timing calibration, enable the Timing Absolute Delay property to adjust the timing reference on synchronized instruments for better timing alignment, measured in seconds.

Trigger Routing

NI-TClk uses the PXI trigger bus to deterministically route triggers among multiple instruments to ensure that all instruments in the system execute at the same time. Deterministic trigger routing ensures that all instruments in the system start at the same time. Refer to multi-device NI-TClk examples for more information about how to use the NI-TClk API and refer to the NI-TClk Synchronization Help for more information on using NI-TClk to synchronize instruments.

Using Matched and Failed Opcode Parameters with Synchronized Digital Pattern Instruments

During a pattern burst, the digital pattern instrument pattern sequencer controls the matched and failed parameters of the jump_if and exit_loop_if opcodes. When you burst patterns that use the matched and failed parameters across multiple synchronized digital pattern instruments, you must complete the following steps to configure the system to combine comparison results across the digital pattern instruments.

• Use the NI-Sync 16.1 or later to initialize the PXIe-6674T timing and synchronization instrument.
• Use the niTClk Synchronize API to align the internal clocks and route the triggers of the digital pattern instruments.
• Use the niDigital Enable Match Fail Combination API to enable each synchronized instrument to process the combined comparison results.

When you configure a system to combine matched and failed results, if a failed condition occurs on any of the sites enabled for bursting on any of the multiple synchronized digital pattern instruments, the combined system result for the failed condition is TRUE and influences the flow of pattern execution through opcodes that use the failed condition as a parameter. Calling the niDigital Get Site Pass Fail API in the test program on all digital pattern instruments returns failed results only for the sites on the instruments that caused the failure.

When you configure a system to combine matched and failed results, the combined system result for the matched condition is TRUE only when the matched condition is satisfied by all sites enabled for bursting across multiple synchronized digital pattern instruments that include pins in the specified match condition.